Ever wonder how polarizing materials were invented? Of course you have. But you probably never would have guessed this:

[Herapathite was discovered by] William Bird Herapath, a physician in Bristol, England, whose pupil, a Mr. Phelps, had found that when he dropped iodine into the urine of a dog that had been fed quinine, little scintillating green crystals formed in the reaction liquid. Phelps went to his teacher, and Herapath then did something which I think was curious under the circumstances; he looked at the crystals under a microscope and noticed that in some places they were light where they overlapped and in some places they were dark. He was shrewd enough to recognize that here was a remarkable phenomenon, a new polarizing material.

Source (PDF). Emphasis mine. Apparently, the modern manufacturing technique came about due to quinine shortages in WWII, though I'm unclear if dogs were still handling the processing at that point.